CORSAIR Mac Memory, 1333MHz C9 DDR3 SODIMM for Apple iMac, MacBook and MacBook Pro 8GB Kit (2 x 4 GB). Tested at Apples compatibility lab to ensure functionality with all current products that have official Apple support for 8GB SO-DIMMs. Adding system memory is one of the most effective ways to improve overall performance and Corsair's Mac Memory offers a solid tested solution with a limited lifetime warranty.